From owner-freebsd-hackers Fri Dec 10 23:17:56 1999 Delivered-To: freebsd-hackers@freebsd.org Received: from mass.cdrom.com (castles536.castles.com [208.214.165.100]) by hub.freebsd.org (Postfix) with ESMTP id 705D314CEC for ; Fri, 10 Dec 1999 23:17:54 -0800 (PST) (envelope-from msmith@mass.cdrom.com) Received: from mass.cdrom.com (localhost [127.0.0.1]) by mass.cdrom.com (8.9.3/8.9.3) with ESMTP id XAA00953; Fri, 10 Dec 1999 23:20:29 -0800 (PST) (envelope-from msmith@mass.cdrom.com) Message-Id: <199912110720.XAA00953@mass.cdrom.com> X-Mailer: exmh version 2.1.1 10/15/1999 To: "Daniel Hilevich" Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: Use of the ppi interface In-reply-to: Your message of "Wed, 08 Dec 1999 17:40:36 +0200." <060901bf4192$926e8350$2e00a8c0@cwnt.co.il> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Fri, 10 Dec 1999 23:20:29 -0800 From: Mike Smith Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG - please only post to one list - please do not post HTML messages to public mailing lists > I'm using the parallel port to control some sort of a hardware (i2c). You should probably use the i2cbb driver for this, as it can be easily tweaked to do what you're trying to do here. > For that I generate pulses using the ppi device (geek port). The problem > is that in some cases, the pulse isn't generated. What I do is sending > an ioctl to make the device high (1) and another ioctl to set the device > low (0). It seems that in some cases, the two commands arrive together > to the device so the pulse isn't wide enough. The timing of the output transitions under ppi are very dependant on what the rest of the system is doing. It's not really suitable for this application as-is; you would be better off either using the 'lpbb' driver or building an external parallel-to-i2c interface adapter. > Does the ppbus layer stores the ioctl's in some sort of a buffer and > than flushes its content to the hardware? No. -- \\ Give a man a fish, and you feed him for a day. \\ Mike Smith \\ Tell him he should learn how to fish himself, \\ msmith@freebsd.org \\ and he'll hate you for a lifetime. \\ msmith@cdrom.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message